The performance of golf equipment is continuously advancing due to the introduction of advanced materials to both golf clubs (irons, woods, and putters) and balls, as well as the development of innovative clubs and club designs such as high loft woods and oversize drivers. While all clubs in the golfer's bag are important, both scratch and novice golfers rely on the performance and feel of their irons for many commonly encountered playing situations.
Irons are generally configured in a set that includes clubs of varying loft, with shaft lengths and clubhead weights selected to maintain an approximately constant “swing weight” so that the golfer perceives a common “feel” or “balance” in swinging both the low irons and high irons in a set. The size of an iron's “sweet spot” is generally related to the size (i.e., surface area) of the iron's striking face, and iron sets are available with oversize club heads to provide a large sweet spot that is desirable to many golfers.
Conventional “blade” type irons have been largely displaced (especially for novice golfers) by so-called “perimeter weighted” irons, which include “cavity-back” and “hollow” iron designs. Cavity-back irons have a cavity directly behind the striking plate, which permits club head mass to be distributed about the perimeter of the striking plate, and such clubs tend to be more forgiving to off-center hits. Hollow irons have features similar to cavity-back irons, but the cavity is enclosed by a rear wall to form a hollow region behind the striking plate. Perimeter weighted, cavity back, and hollow iron designs permit club designers to redistribute club head mass to achieve intended playing characteristics associated with, for example, placement of club head center of mass or a moment of inertia.
While perimeter-weighted designs offer more design possibilities than blade type designs, perimeter weighting can result in clubs with an undesirable “feel.” In addition, even with perimeter weighting, significant portions of club head mass, such as the mass associated with the striking plate, are unavailable for redistribution. Additional design flexibility is needed for improved club heads and clubs.